Installation instructions

Create a concatenated .pem file
Once you received your certificate files, open the primary domain certificate (your_domain_name.crt) in a text editor like Notepad.
Following the primary certificate paste the Private Key file (your_domain_namem.key).
Make sure to include all information like:

-----BEGIN CERTIFICATE-----
 (your_domain_name.crt)
 -----END CERTIFICATE-----
 -----BEGIN RSA PRIVATE KEY-----
 (your_domain_name.key)
 -----END RSA PRIVATE KEY-----

Save this file as a .pem bestand.

Intermediate Certificate
Open the Intermediate certificate in e text editor and save it as a .txt file.

Secure IMAP
Find and open the imapd-ssl file (usually located in /usr/lib/courier-imap/etc/)
Add the following lines:

- TLS_CERTFILE=/path/filename.pem (the .pem file see step 1)
- TLS_TRUSTCERTS=/path/filename.txt  (the text file see step 2)

At the next line set SSL3:

TLS_PROTOCOL=SSL3

Secure POP3
Find and open the pop3d-ssl file (usually located in  /usr/lib/courier-imap/etc/).
Add the following lines:

- TLS_CERTFILE=/path/bestandsnaam.pem (the .pem file see step 1)
- TLS_TRUSTCERTS=/path/bestandsnaam.txt  (the text file see step 2)

File permissions
Make sure the .pem file is only readable by 'root' 

Restart Courier-IMAP server